When we multiply two of the same numbers together, such as , we say that we are squaring the number. We can write it like this:

The raised 2 in is called an exponent.

Because , we write  and we say, “5 squared is 25.”

When we multiply three of the same numbers together, such as , we say that we are cubing the number. We can write it like this:

Because , we write and we say, “4 cubed is 64.”

We also use an exponent for square units and cubic units.

• A square with a side length of 5 inches has an area of 25 in².
• A cube with an edge length of 4 cm has a volume of 64 cm³.

To read 25 in², we say “25 square inches,” just like before.

The area of a square with a side length of 7 kilometers is km². The volume of a cube with an edge length of 2 millimeters is  mm³.

In general, the area of a square with a side length of is , and the volume of a cube with an edge length of is .